[Value of prospectively electrocardiography-triggered high-pitch computed tomography in the follow-up of patients with previous coronary stent implantation].

OBJECTIVE: To explore the value of prospectively ECG-triggered high-pitch spiral mode CT coronary angiography (CTCA) in the follow-up of patients with prior coronary stent implantation.

METHODS: According to the different scan modes, ninety-six patients with heart rate below 75 beat per minute, sinus rhythm and weight below 100 kg and previous coronary stent implantation who underwent 128-slice dual-source Flash spiral CT coronary angiography were randomly divided into two groups according to the randomly numbers in the envelopes: group A(the prospective electrocardiography gated group, 50 cases) and group B(the prospectively ECG-triggered high-pitch spiral mode group, 46 cases). The image quality was evaluated with a four-point grading scale (1 = excellent, 2 = good, 3 = poor, 4 = very poor or non-diagnostic). The total effective dose and the total dose length product between the two groups were recorded respectively. The CTCA enhanced effective dose, dose length product, and the CT volume dosage index (CTDIvol) between the two groups were recorded respectively.

RESULTS: A total of 157 stents were implanted, there were 78 stents in group A and 79 stents in group B, and the value of the image quality was (1.3 ± 0.6) scores in group A and (1.4 ± 0.6) scores in group B (P > 0.05). The total effective dose [(7.6 ± 1.8) mSv vs. (1.6 ± 0.3) mSv] and dose length product [(545.8 ± 131.5) mGy×cm vs. (111.4 ± 19.8) mGy×cm]of the entire scan process were significantly higher in group A than in group B (all P < 0.01). The CTCA enhanced effective dose [(6.7 ± 1.7) mSv vs. (1.2 ± 0.2) mSv], dose length product [(480.8 ± 121.9) mGy×cm vs. (84.2 ± 17.5) mGy×cm] and the CTDIvol [(35.7 ± 8.6) mGy vs. (4.5 ± 0.9) mGy] of group A were also significantly higher than those in group B (all P < 0.01).

CONCLUSIONS: It is clinically feasible to use the dual-source Flash spiral CT coronary angiography for the follow-up of the patients with previous coronary stent implantation. This new process can substantially reduce the radiation dose while preserving good imaging quality.